From the prior art there is known, for example, the document DE 10 2008 001 607 A1. This relates to an electric machine for a vehicle, especially a motor vehicle, having a rotor with a rotor shaft and possessing a cooling device with a coolant. It is proposed that the rotor shaft is designed as a hollow shaft having an internal wall, through which coolant flows, having in its interior at least one coolant delivery element connected to the internal wall of the hollow shaft and delivering coolant by way of its rotation along with the hollow shaft.
Furthermore, the document DE 10 2011 015 623 A1 describes an electric drive unit for a motor vehicle, having an electric machine and a lubrication and cooling circuit. The lubrication and cooling circuit comprises an aqueous lubricant that is conducted at least through an internal space of the electric machine, in order to cool parts of the electric machine in the internal space.